Regulating system



Jm 1944- v G. E. KING ErAL REGULATING SYSTEM Filed Jan. 8, 1943 INVENTORS.

ffalph Geise man.

George E. h in and Patented Jan. 25, 1944 REGULATING SYSTEM George E. King and RalphA. Geiselman, Wilkinsburg, Pa., assignors to Westinghouse Electric &' Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 8, 1943, Serial No. 471,662

7 Claims.

This invention relates generally to regulating systems and, in particular, to regulating systems for milling machines or the like.

In industry, many planing, cutting and milling machines are used for dressing different types of work. The work is usually carried on a movable work table which is operated by a feedmotor with the cutting or milling tool operated by a motor at a certain speed depending upon the speed of the feed motor and the type of work. In such cases, the cutting motor is usually operated at full load, the feed motor being operated to feed the work to the cutter at a rate sufficient to maintain the full load on the cutter.

It is a relatively simple matter to provide a regulating system for such milling machines which utilize one cutting tool but wherea plurality of cutting tools are to be operated, thus necessitating a plurality of cutting motors, it becomes quite diflicult to provide a satisfactory regulating system for controlling the speed of the feed motor in response to variations in the load of any one or all of the different cutter motors.

It is an object of this invention to provide, in

a machine tool having a feed motor and a plurality of cutter motors, for controlling the speed of the feed motor in response to the loads on the .difierent cutter motors.

Another object of this invention is to provide, in a machine tool having a feed motor and a plurality of cutter motors, for decreasing the speed of the feed motor in response to an overload on any one of the motors.

A further object of this invention is to provide, in a machine tool having a feed motor and a plurality of cutter motors, for decreasing the speed of the feed motor in response to an overload on any one of the motors and to increase the; speed of the feed motor only in response to a predetermined operation of all of the motors.

Other objects of this invention will become apparent from the following description when taken in conjunctiori with the accompanying drawing, the single figure of which is a diagrammatic view of the apparatus and circuits embodying the teachings of this invention.

Referring to the drawing, this inventionis illustrated as applied to a machine tool I0, fragmentarily shown as comprising a work table l2 carrying work I4, disposed to be driven through a worm and gear drive I6 by a feed motor I8. A pluralityof cutters 20, 22 and 24 are illustrated as disposed to be operated by cutter motors 26,

28 and 30, respectively, to perform predetermined operations on the work I4.

The feed motor I8 comprises a separately excited field winding 32 and an armature winding 34 disposed to be connected by the switch 36 to a constant source of power represented by supplyv conductors 38 and 40. The field winding 32 of the feed motor I8 is connected in series with the primary windings '66, 68, I0 and 12 of damping transformers I4, 16, 18 and 80, respectively, the purpose of which will be explained more fully hereinafter and the armature winding 82 of an exciter 84, such series connected elements being disposed to be connected to supply conductors 38 and 40 by switches 86 and 88, respectively.

Each of the cutter motors 26, 28 and 30 has an armature winding 42, Hand, respectively, disposed to be connected by a switch 48, and 52, respectively, to supply conductors 38 and 40, the motors each having a commutating field winding 54, 56, and 58, respectively, connected in series with the armature winding of the respective motors. A shunt field winding 60, 62 and 64 is also provided for each of the cutter motors 26, 28 and 30, respectively.

The exciter 84 is provided with a field winding 90 which is connected across terminals 82 and 94 of a resistance bridge66 formed by the resistor legs 98-I00 and I02-I04 connected between terminals I06 and I08. The terminal I06 of the resistance bridge 86 is connected by conductors H0 and H2 to the conductor 4' and the switch 86 while the terminal I08 is connected by conductor I I6 to conductor I I8 and the switch 88, whereby the bridge 96 is disposed to be connectedacross supply conductors 38 and 40.

As illustrated, each of the cutter motors 26, 28 and 30 and the feed motor I8 is provided with a regulating relay I20, I22, I24 and I26, respectively. Each of the relays I20, I22, I24 and I26 is of the same general type disclosed in Patent 1,820,712, issued August 25, 1931, to W. Schaelchlin, and assigned to the assignee of this invention, and comprises a magnetic core member I28, I30, I32 and I34, respectively, having a main energizing winding I36, I38, I40 and I42, re-' spectively, disposed thereon, a pivotally mounted armature member I44, I46, I48, and I50, respectively, having an auxiliary energizing winding I52, I54, I56, and I58, respectively, disposed thereon in a predetermined manner. A spring member I60, I62, I64 and I66 is provided'for each of the relays I20, I22, I24 and I26, respectively, disposed to bias the armature member of therespective relays against the magnetic pull of the energizing winding, a contact member ,I88, I10, I12 and I14, respectively, being carried by the armature member and disposed for movement therewith. As illustrated, the main energizing windings I38, I38, I40 and I42 of the relays I20, I22, I24 and I26, respectively, are connected in series circuit relation with each other and with a resistor I18 across conductors H2 and H8 and are maintained at a constant energization when the switches 86'and 88 are in their circuit closing position to connect the conductors H2 and 1 I8 to supply conductors 38 and 40.

As illustrated, the auxiliary energizing winding I52 of relay I20 is disposed with its one endconnected through an adjustable rheostat I18 to one terminal of the commutating winding 84 of the associated cutter motor 28, the other end of the winding I52 being connected through-the secondary winding I80 of a damping transformer I82 and the secondary winding I84 of the damping transformer 80 to the other end of the commutating winding 54. The primary winding I8I of the damping transformer I82 is connected by conductors H2 and I83 across the armature 82 of the exciter 84 so that the change in voltage across the winding I8I is a measure of the change across the armature 82..

The auxiliary energizing windings I54 and I58 of the relays I22 and I24 respectively, are likewise connected across the commutating windings 58 and 58, respectively, of the associated cutter motors 28 and 30 through series connected secondary windings of damping transformers I85-18 and I81-18 respectively, in a manner similar to the connection of the auxiliary energizing winding I52 of relay I20.

Likewise the auxiliary energizing winding I58 the other contact member 200 being connected to a conductor 202.

The relay I24 is also provided with contact members 204 and 208 for cooperating with the movable contact member I12, one of the contact members 204 being connected to conductor I90, the other contact member 204 being connected to conductor I92. As illustrated, one of the contact members 208 is connected to conductor 202 while the other contact member 208 is connected to conductor 208.

The feed motor relay I28 has its movable contact member I14 disposed for operation between contactmembers 2I0 and 2 I2, one of the contact members 2I0 being connected to conductor I90 and the other contact member 2I0 being connected through a conductor 2I4 to one of the contact members 2I2 which is connected to conductor I92. The other contact member 2I2 is connected to conductor 208.

Thus when all of the contact members I88, I10, I12 and I14 are actuated in a counterclockwise direction into engagement with their left-hand contact members, a series circuit is completed to shu'nt the leg I04 of resistance bridge 98 and connect the field winding 90 of the exciter 84 in such a manner as to buck the normal flow of current through the field winding 32 of the feed motor I8 and efiect an increase in the speed of the feed motor I8. On the other hand, if any one of the contact members I88, I10, I12 and I14 of the relay I28 is disposed to have its one end connected by conductor M8 to one terminal of the field winding 32 of the feed motor I8, the other end of the winding I58 being connected through an adjustable resistor and the series connected secondary windings of damping transformers I89-I4 to the other end of the field winding 32 in the same manner as the connection of the auxiliary windings of relays I20, I22 and I24 across the commutating field winding of their associated cutter motors. As illustrated the primary windings of each of damping transformers I85, 'I 81 and I89 are connected in parallel with the primary winding of transformer I82 across the armature winding 82 of the exciter 84.

The movable contact member of each of the relays I20, I22, I24, and I28 is disposed for movement between opposed contact members for controlling the direction of current flow through the field winding 90 of the exciter 84. As illustrated,- the contact member I88 of relay I20 is disposed for movement between contact members I88 and I88, one of the contact members I88 being connected to a conductor I90 which is connected to the terminal 92 of the resistance bridge 98, the other contact member I88 being connected by a conductor I92 to the terminal I08 of the resistance bridge 98. One of the contact members I88 is connected by a conductor I94 to the terminal 94 of the bridge 98, the other contact member I88 being connected to a conductor I98.

Similarly, the movable contact member I10 of relay I22 is disposed for movement between contact members I98 and 200, one of the contact members I98 also being connected to the conductor I90, the other contact member I98 being connected to theconductor I92. One of the contact members 200 is connected to conductor I98,

is actuated in a clockwise direction to bridge its associated right-hand contact members, then a circuit is completed from the terminal I08 of the bridge 98 through conductor I92 and the closed right-hand contact members of any one of the relays and conductor I to the terminal 92 to' shunt the leg I00 of the bridge 98 and thereby so connect the field winding 90 of the exciter 84 that the output of the exciter 84 will boost the normal flow of current through the field winding 32 of the feed motor I 8 and thereby eifect a decrease in the speed of the feed motor.

In operation, assuming that the switches 48, 50, 52, 88 and 88 are actuated to their circuit closing position and that the feed motor I8 and the cutter motors 28, 28 and 30 are energized with the adjustable resistor associated with each of the relay I20, I22, I24 and I28 so adjusted that the magnetic pull of the main energizing widings of each of the relays balances the mechanical pull of the spring member associated with the armature member of the relays, the cutter motors and feed motor will operate at the maximum speed for maximum loading of the cutter motors. For this normal operation of the feed motor and the cutter motors and with the energization of the main windings I38, I38, I40 and I42 of the relays I20, I22," I24 and I28, respectively, at a constant value, it is apparent that the movable contact members of the respective relays are vibrating into and out of engagement with their associated left-hand contact members.

If for any reason, any one of the cutter motors, forexanrple, cutter motor 28, is overloaded, then the current in the commutating field winding 54 of motor 28 is increased with the result that the auxiliary field winding I52 of relay I20 is so energized as 'to actuate the contact member I88 to bridge the contact members I88. The bridging of contact members I88 closes a circuit which extends from the terminal I08 of bridge H tacts members.

crease in the speed of the feed motor I8 and, in

efi'ect, remove the overload condition from the cutter motor 26. As the flow of current through the field winding 82 of feed motor I8 increases,

former 88 and the primary winding of damping r transformer I82 which is connected across the armature 82 of the exciter 84 is increased to induce a flow of current in the auxiliary winding circuit of the relay I28 which is in opposition to the normal flow of current occasioned by the drop across the commutating winding 54 of the cutter motor 26. The efiect of such a decrease in the energization of the auxiliary winding I52 of relay I28 is immediate and in anticipation of the change in the load conditions on the cutter motor 26. Such a decrease in the energization of the winding I52 permits the spring I68 to actuate the contact member I68 away from the contactmemb'ers I86 to interrupt the shunting -circuit around the leg I88 of the bridge 96, and,

bers I86 is a fast vibrating movement as the overload condition is removed, the damping cutter motors.

transformers I82 and 80 providin satisfactory anti-hunt control.

A similar operation for any one of the cutter motors 28 and 38 and for the feed motor I8 is obtained where any one of these motors is overloaded, the associated relay I22, I24, and I26, respectively, being disposed to connect the field winding 98 of the exciter 84 in the manner described hereinbefore with respect to the operation of the cutter motor 26 to increase the excitation of the field winding 32 of the feed motor I8 and effectively decrease the speed of the feed motor to thereby remove the overload condition. Similarly, the damping transformers connected in series with the auxiliary energizing winding of each of the relays I22, I24 and I26 functions to anticipate the corrective action and to prevent overcorrection in the operation of the feed motor I8.

. ,On the other hand, if the load of cutter motor 26 is decreased, then the auxiliary winding I52 of the associated relay I28 is deenergized to permit the movable contact members I68 to engage the contact members I88. The operation of the contact member I68 to bridge the contact members I88 fails to produce any corrective operation of exciter 84 as long as any one of the contact members I18, I12 and I14 of the relays I22, I24 and I26, respectively, is in a position other than that of bridging its associated left-hand con- However, if the auxiliary windings I54, I56 and I58 of the relays I22, I24 and I26, respectively, are so deenergized that the movable contact members I18, I12 and I14 are in their left-hand position bridging contact members 288, 286, and 2I8, respectively, then the movement of the actuating member I68 of relay I28 to bridge the contact members I 88 is effective for establishing a series circuit to shunt the leg I84 0! bridge 86. This shunting circuit may be traced from the terminal 84 of the resistance bridge 86 through conductor I84, contact members I88 and I68, conductor I86,-contact members 288 and I18, conductor 282, contact members 286 and I12, conductor 288, contact members 2I2 and I14 and conductor I82 to the ter-' minal I88 of the bridge 86. The shunting of the leg I84 so connects the field winding 98 of the exciter 84 that the output of the exciter 84 is in opposition to the normal flow of current through the field winding 32 of the feed motor I8 to effect a'decrease in the energization of the field winding 82 and thereby effect an increase in the speed of the feed motor I8.

Again, the damping transformers associated with each of the relays I28, I22, I24 and I28 function to" anticipate the corrective action to prevent increasing the speed of the feed motor to such a degree as to overload any one of the As will be apparent, the flow of current in the auxiliary energizin winding circuit of the relay I28 in opposition to the normal flow o'fcurrent will be greatly reduced by the decrease in the current supplied to the field wind ing of the feed motor whereby, in effect, the energization of the energizing winding I52 is in creased to efiect the movement of the movable contact member I68 away from the contact members I88 to interrupt the shunting circuit about the leg I84 of the resistance 96. Similarly, any one of the relays I28, I22, I24-and I26 will respond to a change in current in their associated damping transformers to operate their movable contact members away from their left-hand contact members to interrupt the shunting circuit about the leg I84.

It is apparent from the foregoing description that an overload on any one of the motors will effect a corrective operation of the feed motor I8 to remove the overload condition whereas it is necessary for all of the relays I28, I22, I24 and I26 to be operated in a predetermined manner to efiect an increase in the speed of the feed motor I8, By providing the system described hereinbefore, it is also seen that the feed motor speed is limited to approximately the speed required for the maximum loading on the cutter motors thereby permitting the speed of the feed motor to be at a high value without forcing the work into the cutter so fast as to damage the cutting tools or to seriously overload the cutter motors.

This latter operation is obtained primarily be- I point where the speed has reached a maximum.

Although this invention has been described with reference to a particular improvement thereof, it is, of course, not to be limited thereto except insofar as is necessitated by the scope of the appended claims.

We claim as our invention:

1. In combination with a machine tool having awork table and a plurality of cutters, a feed motor having a field winding disposed to drive the work table, a motor for driving each of the ling the connection of the field winding of the' exciter to control the speed of the feed motor, one' of the relays being responsive to the field winding of the feed motor and each of the other relays being responsive to the armature current of an associated cutter motor.

2. In combination with a machine tool having a work table and a plurality of cutters, a feed motor having a field winding disposed to drive the work table, a motor for driving each of the cutters, each of the cutter motors having an armature winding and field winding, an exciter having an armature winding connected in series circuit relation with the field winding of the feed motor, a field winding for the exciter disposed to be connected to control the energization of the feed motor, a relay responsive to the field winding of the feed motor, and a relay associated with and responsive to the armature current of each of the cutter motors, each of the relays having a circuit closing member disposed to be actuated in the one or the other direction, each of the circuit closing members being disposed when actuated'in the one direction to connect the field winding of the exciter to effect an increase in the energization of the field winding of the feed motor, the' circuit closing members also being disposed to connect the field winding of the exciter to effect a decrease in the energization of the field winding of the feed motor when only all of the circuit closing members are actuated in the other direction.

3. In combination with a machine tool having a work table and a plurality of cutters, a feed motor having a field winding disposed to drive the work table, a motor for driving each of the cutters, each of the cutter motors having an armature winding and a field winding, an exciter having an armature winding connected in series circuit relation with the field winding of the feed motor, a field winding for the exciter disposed to be connected to control the energization of the feed motor, means responsive to the feed motor and cutter motors for controlling the connection of the field winding of the exciter to control the speed of the feed motor, and means comprising damping transformers connected in circuit relation with the feed motor andthe exciter for affecting the controlling means in anticipation of a correction of the speed of the feed motor.

4. In combination with a machine tool having a work table and a plurality of cutters, a feed motor having a field winding disposed to drive the work table, a motor for driving each of the cutters, each of the cutter motors having an armature winding and a field winding, an exciter having an armature winding connected in series circuit relation with the field winding of the feed motor, a field winding for the exciter disposed to be connected to control the energization of the feed motor, means comprising damping transformers connected in circuit relation with the feed motor and exciter and each of the relays for affecting the operation of the relay connected in circuit therewith in anticipation of a correction winding of the exciter to control the speed of the feed motor, one of the relays being responsive to the field winding of the feed motor and each of the other relays being responsive to the armature current of an associated cutter motor.

5. In combination with a machine tool having a work table and a plurality of cutters, a feed motor having afield winding disposed to drive the work table, a motor for driving each of the cutters, each of the cutter motors having a commutating field winding, an exciter having an armature winding connected in series circuit relation with the field winding of the feed motor, a field winding for the exciter disposed to be connected to control the energization of the field motor, a relay responsive to the field winding of the feed motor, a relay associated with and responsive to the commutating field winding of each of the cutter motors, each of the relays having a circuit closing member disposed to be actuated in the one or the other direction, each of the circuit closing members being disposed when actuated in the one direction to connect the field winding of the exciter to effect an increase in the energization of the field winding of the feed motor, the circuit closing members also being disposed to connect the field winding of the exciter to effect a decrease in the energization of the field winding of the feed motor when only all of the circuit closing members are actuated in the other direction, and means comprising damping transformers connected in circuit relation with the feed motor and exciter and each of the relays for affecting the operation of the relay connected in circuit therewith in anticipation of a correction of the speed of the feed motor.

6. In combination with a machine tool having a work table and a plurality of cutters, a feed motor having a field winding disposed to drive the work table, a motor for driving each of the cutters, each of the cutter motors having a commutating field winding, an exciter having an armature winding connected in series circuit relation with the field winding of the feed motor, a field winding for the exciter disposed to be connected to control the energization of the feed motor, a relay having an energizing winding connected across the field winding of the feed motor, a relay having an energizing winding connected across the commutating field winding of each of the cutter motors, each of the relays having a circuit closing member disposed to be actuated in the one or the other direction for controlling the connection of the field winding of the exciter to control the speed of the feed motor, and means comprising damping transformers connected in circuit relation with the feed motor and exciter and the energizing winding of each of the relays for affecting the operation of the relay connected in circuit therewith in anticipation of a correction of the speed of the feed motor.

7. In combination with a machine tool having a work table and a plurality of cutters, a feed motor having a field winding disposed to drive the work table, a motor for driving each of the cutters, each of the cutter motors having a commutating field winding, an exciter having an armature winding connected in series circuit relation with the field winding of the feed motor, a field winding for the exciter disposed to be connected to control the energization of the feed motor, a relay having an energizing winding connected across the field winding of the feed motor, a relay having an energizing winding connected across the commutating field winding of each of the cutter motors. each of the relays havinga circuit closing member disposed to be actuated in the one or the other direction, eachof the circuit closing members being disposed when actuated in the one direction to connect the field winding of the exciter to eflect an increase in the energizationot the field winding of the feed motor, the circuit closing members also being disposed to connect the field winding of the exciter toefiect a decrease in the energization of the field winding of the feed 10 motor when only all of the circuit closing members are actuated in the other direction, and means comprising damping transformers connected in circuit relation with the feed motor and the exciter and the energizing winding of each of the relays for effecting the operation of the relay connected in circuit therewith in anticipation of a correction of the speed of the feed motor. GEORGE E. KING. RALPH A. GEISmMAN. 

